I am a cyclist. I am always
incredibly wary when I see drivers using their phones. Yes, this happens a lot, and yes I am in the habit of looking very carefully if drivers have seen me or not. Usually they don't and drive as if I don't exist – it's so frequent that I am nearly driven over, that I have become a rather defensive cyclist. But indeed, apart from random aggressive people (e.g., just yesterday on my way home from work, a car shaved past me at rather high speed (about 50-60km/h at 10cm max) with youths shouting at me) on of my biggest gripes is people who text at the wheel. It's insane.
(disclosure: I live in France, and as far as cycling culture/acceptance and infrastructure is concerned, this is a third-world country)